Probably like it does with 2011 and 2012 and 2013 Macs with Thunderbolt interface and non-Thunderbolt displays, with an appropriate adapter, if the display has no Mini DisplayPort interface and at the end of the chain.
And probably with some restrictions. I think there are three thunderbolt controllers which I believe mean one non-TB display per, so three possible legacy monitors plus one on the HDMI for four. Which is pretty optimal, three monitors is ideal IMO.